Physicochemical Changes and Possibility of Eutrophication by a Water Transfer to International Parishan Wetland, Iran.

Abstract

The international Parishan Wetland, Iran, has completely dried up since 2009. Efforts are underway to restore it through the water transfer from the under-construction Nargesi dam. The aim of this research is to study the physicochemical effects the possibility of eutrophication in this wetland after this function. Sampling was conducted from active springs and the freshwater river (behind the Nargesi dam). The physicochemical parameters were measured and compared with those obtained during wet years. The average electrical conductivity (EC) of the water in the Nargesi dam and the wetland after the water transfer, were calculated considering an annual input of 15 mcm. The results indicated that with transferring during rainy months, after 7-10 years, EC, salinity, hardness, and total dissolved solids (TDS) of the wetland water will reach a similar long-term level as wet years. After this period, if water continues to be supplied from the dam, the salinity of the wetland will increase, reaching a higher level of 0.25-0.27 g/l per year and after 10 years, it will be 2.5-2.7 g/l. However, such changes are not expected to cause significant ecological contradictions in the ecosystem conditions due to the euryhaline nature of aquatic animals of Parishan wetland. Despite the concentration of nitrate and phosphate in the two water sources, due to the high pH and alkalinity of the wetland water, as it was in the wet years, these two nutrients are not limiting factors for production, and according to the high pH and high alkalinity, eutrophication will not occur.